The objective of the project is to understand how gene activity is controlled in early development in sea urchin embryos and in mouse embryos. Using cloned genes for snRNAs we will determine the sequences required for correct developmental regulation of gene expression. We will use an in vivo system, microinjection of DNA into sea urchin embryos, and an in vitro s- dependent system which we have developed. Protein factors involved in transcription and 3' end formation of the sea urchin U1 RNA will be characterized and we will attempt to detect factors involved in developmental regulation. We will also determine the sequence requirements for correct tissue-specific expression of the mouse U1b genes. Additional sea urchin snRNA genes will be isolated and characterized.